1. Field of the Invention
This invention relates to a terminal connection method for a switch, and more particularly to a method of and apparatus for connecting terminals where a network is formed from a plurality of switches.
2. Description of the Related Art
Conventionally, in order to connect terminals via a plurality of switches, a line from an originating switch in which a terminal which has developed a request for connection is accommodated to a terminating switch in which another terminal to which the terminal is to be connected is accommodated is acquired, and connection request information is sent out from the originating switch to the terminating switch.
More particularly, as shown as a conventional example in FIG. 1(a), when a calling person performs, while telephone 64 and telephone 65 are first connected to each other via switches 61, 62 and 63 and lines 67 and 68, a dialing operation in order to call telephone 66 which belongs to switch 63 from telephone 64, dial information is sent to switch 63 via line 69 and switch 62 as well as line 70.
Then, switch 63 connects telephone 66 corresponding to the received dial information to line 70 to establish three-party communication by telephones 64, 65 and 66. In this instance, four lines are used to interconnect telephones 64, 65 and 66.
Meanwhile, as shown as another conventional example in FIG. 1(b), when telephone 64 and telephone 65 are first in a mutually connected condition via switches 61, 62 and 63 and lines 67 and 68 and then a calling person performs a dialing operation in order to call telephone 66 which belongs to switch 62 from telephone 64, dial information is sent to switch 62 via line 69.
Then, switch 62 connects telephone 66 corresponding to the received dial information to line 69 to establish three-party communication by telephones 64, 65 and 66. In this instance, three lines are used to interconnect telephones 64, 65 and 66.
Here, the problem of the prior art resides in that, as the scale of the switched network increases, the number of times by which a situation that an all busy condition of lines is encountered and a necessary service cannot be provided when it is required occurs increases. Accordingly, in order to improve the service capability, a large number of line equipments must be installed.
The reason is: in order to connect terminals via a plurality of switches, a line from an originating switch in which a terminal which has developed a request for connection is accommodated to a terminating switch in which another terminal to which the origination terminal is to be connected is accommodated is acquired, and connection request information is sent out from the originating switch to the terminating switch. Therefore, as the number of switches via which the connection request information is transmitted increases, also the number of lines used increases, and also the probability that an all busy condition is encountered increases.